Team:Paris/Production overview Tol/Pal

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Overview

A. Tol/Pal

The bacterial membrane consists of extracellular elements: proteins, polysaccharides, lipids. It is the membrane which gives to the bacteria its shape. There are two big types of bacteria, put in evidence by the Gram tint. (Gram + and gram-).

E. Coli is gram-. Its membrane is more complex. It includes two membranes: the inner membrane and the outer membrane. Between both, there is a thin layer of peptidoglycan.

The outer membrane presents lipo-polysaccharides (LPS). It plays the role of barrier defender against a certain number of agents as antibiotics. They allow to pass nourishing elements, waste of the metabolism. We find porins and other carriers there. There are receivers for the entrance of nourishing elements, receivers in pili ( bacterial conjugation), receivers where settles bacteriophage. It thus has properties of selective permeability, protection and support. Numerous protein complexes are in place to maintain the stability between the inner membrane and the outer membrane.

In particular the system called Tol-Pal consisted of five proteins, TolA, TolB, TolQ, TolR and Pal. This complex allows to maintain the integrity of the wall. Studies showed that if we destabilize this system, we also destabilize the membrane, leading then a production of vesicles. But when the membrane of the bacteria stays for such a long time in this state of destabilization, the bacteria produces too many vesicles and go in state of lysis.

What is Tol-Pal complex ?

The five proteins organised this complex. The TolA/Q/R proteins form a protein complex in the inner membrane. TolB is a periplasmic protein associated with Pal, a lipoprotein. Pal is anchored to the outer membrane and interacts with the peptidoglycan layer. There are interactions with TolA–Pal and TolA–TolB.

References

^Transmembrane a-helix interactions are required for the functional assembly of the escherichia coli Tol complex. Lazzaroni & Geli 1995 - [http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=179564 179564]
^The Tol-Pal proteins of the Escherichia coli cell envelope an energized system required for outer membrane integrity. Lloubès & Journet 2001 - [http://www.ncbi.nlm.nih.gov/pubmed/11501670 11501670]
^Improved methods for producing outer membrane vesicles in gram-negative bacteria. Henry & Lloubès 2004 - [http://www.ncbi.nlm.nih.gov/pubmed/15249060 15249060]

[1] Transmembrane a-helix interactions are required for the functional assembly of the escherichia coli Tol complex. Lazzaroni & Geli 1995 - [http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=179564 179564]

[2] The Tol-Pal proteins of the Escherichia coli cell envelope an energized system required for outer membrane integrity. Lloubès & Journet 2001 - [http://www.ncbi.nlm.nih.gov/pubmed/11501670 11501670]

[3] Improved methods for producing outer membrane vesicles in gram-negative bacteria. Henry & Lloubès 2004 - [http://www.ncbi.nlm.nih.gov/pubmed/15249060 15249060]

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 ==A. Tol/Pal==
-La paroi bactérienne est composée d'éléments extracellulaires : protéines, polysaccharides, lipides. C'est la paroi qui donne à la bactérie sa forme. Il y a deux grands types de bactéries, mis en évidence par la coloration de Gram. (gram + et gram -).
+The bacterial membrane consists of extracellular elements: proteins, polysaccharides, lipids. It is the membrane which gives to the bacteria its shape. There are two big types of bacteria, put in evidence by the Gram tint. (Gram + and gram-).
-E. Coli fait partit du groupe des gram -. Sa paroi est plus complexe. Elle comprend deux membranes : la membrane plasmique et la membrane externe. Entre les deux, il y a une couche mince de peptidoglycane.
+E. Coli is gram-. Its membrane is more complex. It includes two membranes: the inner membrane and the outer membrane. Between both, there is a thin layer of peptidoglycan.
-La membrane externe présente des lipo-polysaccharides (LPS). Elle joue le rôle de barrière protectrice contre un certain nombre d'agents comme les antibiotiques. Elles laissent passer des éléments nutritifs, des déchets du métabolisme. On y trouve des porines et d'autres transporteurs. Il y a des récepteurs pour l'entrée d'éléments nutritifs, des récepteurs à pili (conjugaison bactérienne), des récepteurs où se fixent les bactériophages. Elle a donc des propriétés de perméabilité sélective, de protection et d'adhésion. De nombreux complexes protéiques sont en place pour maintenir la stabilité entre la membrane interne et la membrane externe.
+The outer membrane presents lipo-polysaccharides (LPS). It plays the role of barrier defender against a certain number of agents as antibiotics. They allow to pass nourishing elements, waste of the metabolism. We find porins and other carriers there. There are receivers for the entrance of nourishing elements, receivers in pili ( bacterial conjugation), receivers where settles bacteriophage. It thus has properties of selective permeability, protection and support. Numerous protein complexes are in place to maintain the stability between the inner membrane and the outer membrane.
+In particular the system called Tol-Pal consisted of five proteins, TolA, TolB, TolQ, TolR and Pal. This complex allows to maintain the integrity of the wall. Studies showed that if we destabilize this system, we also destabilize the membrane, leading then a production of vesicles. But when the membrane of the bacteria stays for such a long time in this state of destabilization, the bacteria produces too many vesicles and go in state of lysis.
-Notamment le système appelé Tol-Pal composé de cinq protéines, TolA, TolB, TolQ, TolR and Pal. Ce complexe permet de maintenir l'intégrité de la paroi. De nombreuses études ont montré que si l'on déstabilise ce système, on déstabilise aussi la membrane, induisant alors une production de vésicules. Mais quand la membrane de la bactérie reste trop longtemps dans cet état de déstabilisation, la bactérie produit alors trop de vésicules et rentre en état de lyse cellulaire.